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SubjectRe: [PATCH] params: make dashes and underscores in parameter names truly equal
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On Thu, 13 Oct 2011 16:41:11 +0200, Michal Schmidt <mschmidt@redhat.com> wrote:
> On 10/13/2011 01:28 AM, Rusty Russell wrote:
> > Idea is solid, implementation has a few quirks. As the name
> > obsolete_checksetup() implies, this was only supposed to be a crutch for
> > old __setup() calls. Modern code should be using module_param() or
> > core_param().
>
> ... instead of __setup()?

Yep.

> No objection to the change in do_early_param() ?

Well, for the moment I've applied that, with parameq and parameqn
reimplemented more cleanly. See below.

> > Did you have a specific example?
>
> The specific example I had in mind was the one from
> Documentation/kernel-parameters.txt:
>
> log_buf_len=1M print-fatal-signals=1
> can also be entered as
> log-buf-len=1M print_fatal_signals=1

Oops.

> Let's see how many __setup() parameters there are:
> $ git grep -E '^__setup\("' |wc -l
> 457
>
> Only the ones with a dash or underscore in the name:
> $ git grep -E '__setup\(".*[_-].*"' | wc -l
> 180
>
> It will take some time.

The easy things have already been done ;)

Just do the non-arch ones, first, and see where that gets us.

Thanks!
Rusty.

From: Michal Schmidt <mschmidt@redhat.com>
Subject: params: make dashes and underscores in parameter names truly equal
Date: Mon, 10 Oct 2011 00:03:37 +0200

The user may use "foo-bar" for a kernel parameter defined as "foo_bar".
Make sure it works the other way around too.

Apply the equality of dashes and underscores on early_params and __setup
params as well.

The example given in Documentation/kernel-parameters.txt indicates that
this is the intended behaviour.

With the patch the kernel accepts "log-buf-len=1M" as expected.
https://bugzilla.redhat.com/show_bug.cgi?id=744545

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (neatened implementations)
---
include/linux/moduleparam.h | 20 ++++++++++++++++++++
init/main.c | 4 ++--
kernel/params.c | 21 ++++++++++++++-------
3 files changed, 36 insertions(+), 9 deletions(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -262,6 +262,26 @@ static inline void __kernel_param_unlock
.str = &__param_string_##name, 0, perm); \
__MODULE_PARM_TYPE(name, "string")

+/**
+ * parameq - checks if two parameter names match
+ * @name1: parameter name 1
+ * @name2: parameter name 2
+ *
+ * Returns true if the two parameter names are equal.
+ * Dashes (-) are considered equal to underscores (_).
+ */
+extern bool parameq(const char *name1, const char *name2);
+
+/**
+ * parameqn - checks if two parameter names match
+ * @name1: parameter name 1
+ * @name2: parameter name 2
+ * @n: the length to compare
+ *
+ * Similar to parameq(), except it compares @n characters.
+ */
+extern bool parameqn(const char *name1, const char *name2, size_t n);
+
/* Called on module insert or kernel boot */
extern int parse_args(const char *name,
char *args,
diff --git a/init/main.c b/init/main.c
--- a/init/main.c
+++ b/init/main.c
@@ -163,7 +163,7 @@ static int __init obsolete_checksetup(ch
p = __setup_start;
do {
int n = strlen(p->str);
- if (!strncmp(line, p->str, n)) {
+ if (parameqn(line, p->str, n)) {
if (p->early) {
/* Already done in parse_early_param?
* (Needs exact match on param part).
@@ -392,7 +392,7 @@ static int __init do_early_param(char *p
const struct obs_kernel_param *p;

for (p = __setup_start; p < __setup_end; p++) {
- if ((p->early && strcmp(param, p->str) == 0) ||
+ if ((p->early && parameq(param, p->str)) ||
(strcmp(param, "console") == 0 &&
strcmp(p->str, "earlycon") == 0)
) {
diff --git a/kernel/params.c b/kernel/params.c
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -67,20 +67,27 @@ static void maybe_kfree_parameter(void *
}
}

-static inline char dash2underscore(char c)
+static char dash2underscore(char c)
{
if (c == '-')
return '_';
return c;
}

-static inline int parameq(const char *input, const char *paramname)
+bool parameqn(const char *a, const char *b, size_t n)
{
- unsigned int i;
- for (i = 0; dash2underscore(input[i]) == paramname[i]; i++)
- if (input[i] == '\0')
- return 1;
- return 0;
+ size_t i;
+
+ for (i = 0; i < n; i++) {
+ if (dash2underscore(a[i]) != dash2underscore(b[i]))
+ return false;
+ }
+ return true;
+}
+
+bool parameq(const char *a, const char *b)
+{
+ return parameqn(a, b, strlen(a)+1);
}

static int parse_one(char *param,

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